PROJECT SUMMARY Although individuals from racial/ethnic and linguistic minority groups make up a considerable?and growing? proportion of the US population, they experience greater unmet need for mental health care than non-Latino Whites. Members of these groups are heavily represented in Medicaid, the largest insurer covering the most vulnerable individuals. And although the Affordable Care Act expanded Medicaid eligibility, research to date has not found that expansions have decreased the gap in mental health treatment between Whites and racial/ethnic minorities. Experts have identified a lack of culturally competent, bilingual/bicultural mental health providers as a factor contributing to the maintenance of these disparities. Similar challenges have been addressed in lower-income countries facing severe workforce constraints through the training of community health workers (CHWs), who originate from the communities they serve and have shown promise internationally as mental health service providers. However, they have not yet typically served in this role in US care delivery systems. State Medicaid-based accountable care organizations (ACOs) are forming in large numbers to provide care coordination via team-based approaches, with accumulating evidence suggesting that this strategy can greatly benefit resource-poor populations. However, many ACOs have not yet incorporated mental health services into their networks, despite the observed link between addressing mental health needs and improving physical health. Building staff capacity to provide these needed services would help ACOs implement evidence-based mental health interventions and improve the overall well-being of their assigned patients. Thus, our proposed collaborative R01 will develop ACO-academic-community partnerships in two demographically different states at different stages of ACO development and test a model that trains CHWs to serve as mental health providers within clinics/physician's organization and community-based organizations linked to ACOs in North Carolina and Massachusetts. This effort should expand ACO infrastructures and increase access to and quality of mental health care for low-income racial/ethnic and linguistic minorities in resource-poor communities. If successful, we will work with our ACO site partners to assess implementation outcomes of adoption, fidelity, maintenance, and explore implementation processes (facilitators and contextual factors) as potential mediators of implementation within diverse clinics, CBOs, and ACO networks.